Paper stabilization heater

ABSTRACT

Apparatus for the heat stabilization of spectrally sensitized printout paper on a continuous basis having means for forming a latent image on the paper; means for transporting the paper into thermal contact with a passive heat shunt and raising the temperature of the paper a predetermined increment; heat reservoir means in thermal contact with the paper for raising the temperature an additional predetermined increment; heater means for raising the temperature of the paper to that required for stabilization of the image; means for maintaining the stabilization temperature for a predetermined period of time while the strip is in motion; means for returning the heat from the paper to the heat reservoir; and additional means for returning heat to the heat shunt.

United States Patent [72] inventor [54] PAPER STABILIZATION HEATER 13Claims. 3 Drawing Figs.

52 u.s.c1 219/388, 96/1: 219/216, 219/347.219/530; 263/6 51 1m.c1F27b9/06, H05b1/02 so FieldolSearch 219/388,

[56] References Cited UNITED STATES PATENTS 6/1963 Dudzik PrimaryExaminer- Volodymyr Y. Mayewsky Attorneys-John G. Mesaros, Alan C. Rose,Ronald W.

Reagin and Alfred B. Levine ABSTRACT: Apparatus for the heatstabilization of spectrally sensitized printout paper on a continuousbasis having means for forming a latent image on the paper; means fortransporting the paper into thermal contact with a passive heat shuntand raising the temperature of the paper a predetermined increment; heatreservoir means in thermal contact with the paper for raising thetemperature an additional predetermined increment; heater means forraising the temperature of the paper to that required for stabilizationof the image; means for maintaining the stabilization temperature for apredetermined period of time while the strip is in motion; means forreturning the heat from the paper to the heat reservoir; and additionalmeans for returning heat to the heat shunt.

PATENTED m 5 m sum 1 or 2 ArroR/My PAPER STABILIZATION HEATER BACKGROUNDor THE INVENTION With the development of cathode ray tube recordingsystems employing fibre optics and oscillographs employing Tungsten,xenon or mercury vapor light sources; one of the primary drawbacks tothe full realization of the potential of this media has been the problemrelating to the stabilization of the image on the paper or fixing" thephotographic emulsion to prevent the loss of image.

Generally a spectrally sensitized heat stabilized printout paper isused. A latent image is formed by exposing the paper to an imageproduced on a suitable electro-optical device such as a cathode raytube. The latent image must then be stabilized by heating the emulsionfor a fixed period of time at a predetermined temperature. The image isthen made visible by a subsequent exposure to any source of ultravioletor visible illumination.

It is accordingly an object of this invention to provide a new andimproved printout paper stabilization heater.

It is another object of this invention to provide a new and improvedpaper stabilization heater for the stabilization of the latent image ona continuous basis. I

It is a further object of this invention to provide a new and improvedprintout paper stabilization heater which is compact and reliable.

It is still another object of this invention to provide a new andimproved printout paper stabilization heater capable of instantaneousstartup utilizing a heat reservoir capable of removing heat from thepaper subsequent to the heat stabilization thereof. 1

It is a still further object of this invention to provide a new andimproved printout paper stabilization heater employing a thermalfeedback to increase the efficiency thereof.

SUMMARY OF THE INVENTION The foregoing and other objects of theinvention are accomplished by providing a trough having an open endthrough which the paper enters and exits, the trough having reflectingsurfaces on the inside thereof. Adjacent the opening is an elongatepassive heat shunt having one surface thereof in proximity to thecathode ray tube which produces the original image, this surface beingadapted for contact with the printout paper subsequent to the formationof the latent image in order to raise the temperature of the paper apredetermined increment. An elongate heat reservoir having an internalheater is disposed beneath the heat shunt within the trough andseparated from the heat shunt by suitable insulating means. One surfaceof the heat reservoir is adapted for continuous contact with theprintout paper for increasing the paper temperature an additionalpredeterminedincrement. An insulator is affixed to the lower end of theheatreservoir. A suitable heating means such as a nichrome strip heateris secured to the insulator and is in contact with the paper to bringthe paper to the image stabilization temperature. The opposite surfaceof the heat reservoir is spaced from the strip paper and reflectivelycoated to substantially maintain the temperature of. the paper at thestabilization temperature for a predetermined period of time which isthe time required at temperature for image stabilization. The strip thenpasses into contact with a second surface of the heat reservoir andreturns a portion of the heat. The strip then exits the trough inthermal contact with the other surface of the heat shunt returning aportion of the heat to the shunt. With the strip in continuous movementat a predetermined speed, the temperature of the paper will be raised tothe stabilization temperature in increments.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 2 shows in diagrammatic form anend view of the apparatus of FIG. 1 showing the travel of the strip ofsensitize paper; and

FIG. 3 shows the heat flow within the paper stabilization heater indiagrammatic form.

DESCRIPTION OF THE PREFERRED EMBODIMENT DESCRIPTION OF THE APPARATUSReferring now to the drawings, and particularly to FIGS. 1 and 2, thereis shown a trough generally designated as It) having a bottom 12,sidewalls l4 and 16 and end walls 18 and 20, with the sidewalls andbottom being gold plated to provide reflecting surfaces. The end wallsand sidewalls define an opening 22 opposite the bottom wall 12, thelength of the opening being generally that ofthe printout paper.

Positioned within the opening but spaced from the sidewalls 14 and 16 inclose proximity thereto there is located an elongate passive thermalshunt 24 which may take the form of an aluminum bar of rectangular crosssection. Abutting the under surface of shunt 24 is an insulator 26 ofgenerally uniform thickness and having a depending portion 28 at eitherend thereof, the purpose of which will hereinafter become obvious. Aheat reservoir 30 is positioned between the depending portions 28 inabutting relationship with the undersurface of the insulator 26. Theheat reservoir 30 is made from any suitable thermally conductivematerial such as aluminum and is generally triangular in cross sectionconfiguration. The heat reservoir 30 has a smooth continuous entrancesurface 32 and an exit surface 34 being stepped inwardly at the lowerportion thereof, the step portion being designated 36. An aperture 38extends the length of the heat reservoir 30 intermediate the entrancesurface 32 and the exit surface 34, the aperture 38 being in alignmentwith apertures 40 in the depending portions 28 of insulator 26. Internalheating means 42 extend through the aligned apertures 38 and 40 and aremechanically held in place by suitable fastening means (now shown) atthe outer surface of depending portions 28. The heating means 42 cantake the form of an electrical resistance heater for example, and isenergized from any suitable source of electrical power (not shown).

At the apex of the lower portion of the heat reservoir 30 there islocated a longitudinal groove 44 adapted to receive an insulator 46which has at least the bottom portion thereof rounded. The insulator 46is secured within the groove 44 by bonding or mechanical fastening.Bonded to the curved surface of the insulator 46 is an electrical stripheater 48 made of nichrome or other similar electrical resistancematerial of low thermal mass (low thermal time constant) which isenergized from any suitable source of electrical power (not shown). Thestrip heater 48 has sufficient area to efficiently transfer heat to thepaper 50 at the maximum paper speed.

As shown in FIG. 2 the shunt 24, the insulator 26, and the heatreservoir 30 are so arranged to provide a continuous surface. Printoutpaper 50 is fed off a payout reel 52 passing in close proximity to asuitable optical device such as fibre optic tube 54 and a screen uponwhich the image is displayed. The sensitized surface of the paper 50faces the image display tube 54. The back surface of the paper 50 entersthe trough 10 at the entrance end designated 56in contact with the sidesurface of the shunt 24, the side surface of the insulator 26, and theentrance surface 32 of heat reservoir 30. The paper then reverses itspath around the nichrome strip heater 48 upwardly in spaced parallelrelationship with the step portion 36 of the heat reservoir 30 and intocontact with exit surface 34 of the heat reservoir 30, the side surfaceof insulator 26, and the side surface of shunt 24 through the exit end58 of the opening 22. The paper is then wound on a takeup reel 60.

METHOD OF OPERATION A suitable printout paper which can be utilized isEastman- Kodak type D-l877 paper which is heat stabilized by theapplication of heat to a temperature of approximately 265 C.

for a period of approximately one second, and the description ofoperation will proceed on the basis of this particular printout paper.It is to be understood, however, that the scope of the invention is notto be limited to the utilization of any specific printout paper and isgenerally applicable to any flexible recording medium where a latentimage is formed and must be subsequently heat stabilized at a specifictemperature for a predetermined period of time in order to fix the imageand make it permanent.

Referring now to FIG. 2, the paper 50 moves at approximately 1.67 inchesper second past the fibre optic tube 54 where a latent image is formedon the paper. For purposes of discussion the paper is at roomtemperature or approximately 20 C. Prior to this internal heater 42 hasbeen energized on a standby basis to maintain the heat reservoir at anaverage temperature of 135 C. A certain portion of the heat is lost(approximately 4 watts) through the insulator 26 to thereby maintain thetemperature of the heat shunt 24 at an average temperature of 80 C. Thenichrome strip heater 48 is thermostatically controlled or maintained ata temperature of approximately 260 C. The strip heater 48 can beenergized upon initial movement of the paper 50 and due to its lowthermal mass it will reach operating temperature by the time the firstimage reaches the strip heater 48.

The heat flow diagram shown in FIG. 4 is based on the specificaforementioned paper and temperatures and heat quantities stated are inreference to this paper. After the latent image is formed the paper 50passes in contact with the shunt '24 where about 55 watts of heat isabsorbed and the temperatact with the entrance surface 32 of heatreservoir 30. An additional 120 watts of heat is conducted from thereservoir to the paper 50 raising its temperature to about 130 C. Thepaper then passes over an open gap and is wrapped around the nichromestrip heater 48 where the temperature of the paper is raised to 260 C.,the temperature required for stabilization. Next, the paper 50 passesover the step portion 36, the portion 36 having a length in thedirection of travel of approximately 1.7 inches. Gold plating of thestep portion 36 and the internal surface of the sidewall 14 of thetrough l minimize radiation and convection losses to substantiallymaintain this temperature. The length of the step portion 36 is chosento require one second for the paper 50 to traverse the step portion 36with the one second being the time period required at the stabilizationtemperature at 260 C., for heat stabilization of the image of thisspecific printout paper.

After stabilization the paper slides over exit surface 34 of the heatreservoir 30. Since the paper 50 is hotter than the reservoir 30 itgives up about 120 watts of heat. The paper then passes over theinsulating section 26 and comes into contact with the heat shunt 24which is still cooler, the paper 50 giving up an additional 55 watts andits temperature is reduced to that of the shunt 24- about 85 C.

The remaining heat is stored in the takeup roll 60 of the paper 50. Thisheat may be transferred by convection to the outsideair or may, to someextent, be transferred to the feed roll to raise the temperature of theunexposed paper.

With this particular apparatus approximately five inches of paper liebetween the fibre optic tube 54 and the viewing area. At the statedspeed of 1.67 inches per second, this means that approximately threeseconds are required between receipt of a message at the tube 50 and itsappearance in the viewing area. When the paper 50 is not moving theheater 42 is switched to standby condition the heat at standby being ashot as possible i but not so hot as to char or mechanically weaken thepaper50 threaded through the apparatus and not moving. ln standby thenichrome strip heater 48 is turned off and the internal heater 42 isturned on and is thermostatically controlled to maintain the temperatureof the heat reservoir at about 135 C. As soon as a message is receivedthe paper 50 begins moving and the nichrome strip heater 48 is switchedon and the internal heater 42 is turned off. With the application ofpower the nichrome strip heater temperature is raised from C standby to260 C., operating temperature within one second or less than the timerequired for the paperto travel from the tube 54 to the nichrome stripheater 48';

in summary, there has been shown anddescribed a printout paperstabilization heater which is compact and efficient, employing heattransfer means to return heat figom the paper to the transfer meansthereby reducing'the,. 1 power requirements from external sources andrendering thegdevice more efficient than heretofore known priorartdeyicesslt is to. be understood, however, that otheradaptationsand,modifications may be made within the spirit and scope ofthe invention,

and the invention is not to be limited by the specificstructure shownnor the specific paper described.

lclaim:

1. Apparatus for the continuous heat stabilization of images formed byexposing to light a strip of light sensitive paper, said apparatuscomprising:

a. a heat reservoir having a first surface in thermal contact with saidpaper subsequent to the formation of the latent image for raising the"temperature of said. paper a predetermined increment; l i an electricalheating element adjacent to but spaced from said heat reservoir, saidheating element being 'in thermal contact with said paper to raise thetemperature .of said paper an additional increment to the temperaturerequired for heat stabilization of the latent iniage;

c. transport means for moving f'i d'ipap'er along a path of travel at apredetermined speed, .j'

d. reflecting means for maintaining 'the paper at the stabilizationtemperature for a predetermined period of time while said paper ismoving at the predetermined speed;

e. thermal conduction means for returninga portion of the heat of saidpaper to said heat reservoiraft rt he l'ap'seof said predeterminedperiod of time; and I f. enclosure means for'substantially containingsaid heat reservoir, said heating element, said reflecting means andsaid thermal conduction means.

2. The combination according to claim 1 wherein said'apparatus isprovided with heat transfer means in thermal contact with said paperprior to said heat reservoir means for raising the temperature of thepaper an initial predetermined increment, said heat transfer meansextracting an additional portion of heat from said paper subsequent tosaid means for returning a portion of the heat of the paper to said heatreservoir.

3. The combination according to claim 1 wherein said heat ing elementincludes an elongate strip heater having a low thermal mass.

4. The combination according to claim 2 wherein said heat.

transfer means includes an elongate bar having first and secondgenerally parallel surfaces, said first surface being in thermal contactwith said paper subsequent to the formation of the latent image and saidsecond surface being in thermal contact with said paper afterstabilization for extracting the heat.

5. The combination according to claim 1 wherein said heat reservoirincludes a thermally conductive block of generally triangular crosssection. I

6. The combination according to claim 5 wherein said strip heater issecured to and insulated from the apex of said block, said strip heaterbeing generally arcuate in configuration for generally reversing thedirection of travel of said paper.

7. The combination according toclaim 6 wherein said block is providedwith a secondgenerally opposite surface vhaving a first portion and asecond portion stepped inwardly from said first portion, said firstportion being adapted for thermal conf tact with the paper for returningheat to said block and said second portion being spaced from the path oftravel of said paper, said secondportion at least partially reflectingheat for maintaining the paper at the stabilization temperature.

8. The combination according to claim 7 wherein said second portion isreflectively coated and the length ol -said' second portion in thedirection of travel of the paper is sufficient to substantially maintainthe paper at the stabilization temperature at said predetermined speed.

9. The combination according to claim 5 wherein said block is providedwith internal heating means.

10. The combination according to claim 9 wherein said internal heatingmeans are energized electrically independent from said strip heater,said internal heatingmeans being energized on a standby basis prior tomovement of the paper to provide an initial heat content to said block,said strip heater being energized upon movement of the paper.

1. Apparatus for the continuous heat stabilization of images formed byexposing to light a strip of light sensitive paper, said apparatuscomprising: a. a heat reservoir having a first surface in thermalcontact with said paper subsequent to the formation of the latent imagefor raising the temperature of said paper a predetermined increment; b.an electrical heating element adjacent to but spaced from said heatreservoir, said heating element being in thermal contact with said paperto raise the temperature of said paper an additional increment to thetemperature required for heat stabilization of the latent image; c.transport means for moving said paper along a path of travel at apredetermined speed; d. reflecting means for maintaining the paper atthe stabilization temperature for a predetermined period of time whilesaid paper is moving at the predetermined speed; e. thermal conductionmeans for returning a portion of the heat of said paper to said heatreservoir after the lapse of said predetermined period of time; and f.enclosure means for substantially containing said heat reservoir, saidheating element, said reflecting means and said thermal conductionmeans.
 2. The combination according to claim 1 wherein said apparatus isprovided with heat transfer means in thermal contact with said paperprior to said heat reservoir means for raising the temperature of thepaper an initial predetermined increment, said heat transfer meansextracting an additional portion of heat from said paper subsequent tosaid means for returning a portion of the heat of the paper to said heatreservoir.
 3. The combination according to claim 1 wherein said heatingelement includes an elongate strip heater having a low thermal mass. 4.The combination according to claim 2 wherein said heat transfer meansincludes an elongate bar having first and second generally parallelsurfaces, said first surface being in thermal contact with said papersubsequent to the formation of the latent image and said second surfacebeing in thermal contact with said paper after stabilization forextracting the heat.
 5. The combination according to claim 1 whereinsaid heat reservoir includes a thermally conductive block of generallytriangular cross section.
 6. The combination according to claim 5wherein said strip heater is secured to and insulated from the apex ofsaid block, said strip heater being generally arcuate in configurationfor generally reversing the direction of travel of said paper.
 7. Thecombination according to claim 6 wherein said block is provided with asecond generally opposite surface having a first portion and a secondportion stepped inwardly from said first portion, said first portionbeing adapted for thermal contact with the paper for returning heat tosaid block and said second portion being spaced from the path of travelof said paper, said second portion at least partially reflecting heatfor maintaining the paper at the stabilization temperature.
 8. Thecombination according to claim 7 wherein said second portion isreflectively coated and the length of said second portion in thedirection of travel of the paper is sufficient to substantially maintainthe paper at the stabilization temperature at said predetermined speed.9. The combination according to claim 5 wherein said block is providedwith internal heating means.
 10. The combination according to claim 9wherein said internal heating means are energized electricallyindependent from said strip heater, said internal heating means beingenergized on a standby basis prior to movement of the paper to providean initial heat content to said block, said strip heater being energizedupon movement of the paper.
 11. The combination according to claim 8wherein said enclosure means includes a trough.
 12. The combinationaccording to claim 11 wherein said trough has an open end for entranceand exit of the paper and oppositely disposed sidewalls in proximity tothe path of travel of the paper.
 13. The combination according to claim12 wherein said trough has end walls and a bottom wall said sidewallsand said bottom wall being reflectively coated.